Effects of Various Methods of Deer Browse Deterrence and Exclusion on Survival of Planted Northern Red Oak Seedlings

Abstract

Northern red oak (Quercus rubra), is a commercially and ecologically valuable timber species in the Lake States that is predicted to have increased habitat suitability in Northern Wisconsin under climate change. Northern red oak is a preferred browse species for white tailed deer (Odocoileus virginianus) and high deer densities have often prevented successful regeneration or establishment of oaks. This study tested three different methods of browse deterrence and exclusion, including paper bud caps, deer repellent spray, rigid mesh tree shelters, vs. a control on recently planted northern red oak seedlings as part of a randomized complete block experiment established at the Treehaven field station in Tomahawk, WI during May of 2020. Data were collected on seedling survival, deer browse, and dieback every successive fall. Previous analysis of this dataset has shown that tree shelters can provide a meaningful reduction in deer browse and increased height growth relative to control. I was interested in whether the treatments led to differences in seedling survival over time so I utilized a logistic regression model to test for differences in survival between treatments. Tree shelters were the most effective at promoting survival, with a 92% survival rate relative to 84% survival of control seedlings. Deer repellant spray had no significant effect when compared to control. Bud capped trees had lower rates of survival at 73% compared to the control. The poor bud cap survival rate indicates that they may increase oak seedling mortality and could be counterproductive in planting efforts.